Preheating device for carburetors



May 6, 1930. E. J. OTTOSSON PREHEATING DEVICE FOR CARBURETORS Filed March 5, 1927 Patented May 6, 1930 UNITED STATES PATENT "01F ICE ERNST JOHAN OTTOSSON, OF YSTAD, SWEDEN, ASSIGNOR T01 OTTO ALFRED ARVASTS- SON, OF MALMO, SWEDEN, AND A.-B. ERNST J." OTTOSSONS ELEMENTFLABRIK, OF YSTAD, SWEDEN, .A CORPORATION OF SWEDEN PREHEATING DEVICE FOR OARBURETORS Application filed March 3, 1927, Serial No. 172,442, and in Sweden June 18, 1926.

This invention relates to a device for preheating air and fuel in a carburetor of the kind in which the liquid level is regulated by a float. It has already been proposed to surround the float chamber with an electric heating device and to protect the latter against external damages by means of a sheet cover. By this means the fuel has been preheated before being sprayed into the com- 1 bustion air, which sometimes is required-in starting the internal combustion engine or during cold weather. It has however been found that also the combustion air should be pre-heated, and to this end the sheet cover a surrounding the electric heating device has according to the invention been replaced by an air heating chamber provided with a valve regulated inlet and an outlet opening into the mixing chamber of the carburetor,

and from this latter chamber the fuel mixture is drawn into the engine cylinders.

The invention is illustrated in the accompanying drawing, in which Fig. 1 shows a vertical section through a carburetor fitted with the air pre-heating chamber according to the invention, and Fig. 2 is a fractional horizontal section on the line IIII Fig. 1.

The carburetor being of a commonly used standard type having a float for regulating the liquid level, it will not be necessary to describe the various elements of this carburetor in detail.

Referring now to the drawing 1 is the float chamber and 2 is the wall of the chamber 35 4 in which the combustion air is pre-heated by means of the electric heating device 3. The air chamber surrounds in an air tight manner the float chamber land is provided with an inlet 5 for fresh air. The inlet has a flap 6 actuated by a spring 7 which tends to keep the flap in closing position. The air chamber is further provided with an outlet 8 which opens into the mixing chamber 9 in front of the ordinary combustion air inlet 10 regulated by a choke valve 11 and behind the fuel spraying device 12, the internal combustion engine being in communication with the mixing chamber by means of the valve regulated conduit 13. t

The function of the device is as follows: When the engine is to be started the choke valve 11 is turned 90 so as to have the position as shown with dash-dotted lines, thus closing the ordinary combustion air inlet 10, and the electric heating device 3 is cut in. During the suction stroke of the engine the flap 6 will be swung against the action of the spring 7 into the position 6* shown with dash-dotted lines, whereby air is drawn in through the inlet 5, and as this air on its way to the outlet 8 is forced to surround the heating device 3 and pass through the chamber 4 which is heated by the said heating device, it will be pre-heated, and at the same time the fuel in the float chamber 1 will be preheated, so that the air-fuel mixture in the chamber 9 will receive a suitable temperature for facilitating the engine to be started. It is obvious that in very cold weather the above described preheating device may be kept continuously in working condition, but otherwise, once the engine has been started, the heatin device 3 may be cut out and the throttle vflve 11 be opened entirely. Under certain circumstances when the air-fuel mixture is to have a medium temperature the heating device 3 may be cut in and the throttle valve 11 be partly opened.

What I claim and desire to secure by Letters Patent is In a carburetor, a body having a float chamber formed with double walls, the space between the walls forming a conduit communicating at one point with atmosphere and at another point with the induction passage of the engine, said body being provided with a main air intake conduit in which is carbureted the liquid fuel supplied from said float chamber, said main air intake conduit also communicating with the said induction passage, an electric heater in the float chamber conduit having the dual function of heating the liquid in the float chamber and heating the air passing through said conduit, and a normally closed valve adjacent the atmospheric inlet in said float chamber conduit; opening responsive to a certain degree of vacuum in said conduit for automatically eX- cluding flow or" air through said conduit at low suction periods in the operation of the engine.

In testimony whereof I have signed my name to this specification.

ERNS' JOHAN OTTOSSON. 

